Inhibition by nitric oxide of ethylene biosynthesis and lipoxygenase activity in peach fruit during storage

The effects of nitric oxide (NO) on ethylene biosynthesis and lipoxygenase (LOX) activity in a climacteric peach fruit (Prunus persica (L.) Batsch., cv. Feicheng) were studied. It was observed that, in peaches treated with 5 and 10 μl l−1 NO, 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase activity, ethylene production and LOX activity were reduced. This led to the accumulation of ACC and 1-malonyl aminocyclopropane-1-carboxylic acid (MACC) during storage. There was no evidence that ACC synthase activity was affected significantly by any concentration of NO. A plausible mechanism is proposed that NO is bound to ACC oxidase to form an ACC oxidase–NO complex, which is chelated by ACC to produce an ACC–ACC oxidase–NO complex, leading to a decrease in ethylene production. The increase in concentration of ACC in NO-treated peaches may result in the redirection of ethylene to MACC production. This is a secondary effect of NO.